Various production related wastewaters arise in many industrial concerns. Normally wastewater is purified in sewage treatment plants by technical processes. The so called nearly natural methods have been used for some time as an alternative to traditional sewage treatment plants for the purification of smaller wastewater streams or amounts of wastewater. When nearly natural methods are used, the self cleaning mechanisms of nature are utilized and, moreover, new wet biotopes and green spaces are created. In addition, such nearly natural methods are associated with considerable cost savings.
Plant based sewage treatment systems, as are already in use in many places, are among these nearly natural methods. A plant based sewage treatment system is based on a biological symbiosis between specially grown water plants and microorganisms, for example bacteria, fungi and algae.
Current plant based sewage treatment systems are mainly operated by private households and communes and are mostly used where connection to a central sewage treatment system is too costly. In these systems plants are planted on soil, gravel or sand (i.e., in a substrate). However, the plant based sewage treatment systems usually require relatively large areas, which are mostly not available, especially in industrial regions. Merely as a matter of example, reference is made to DE 196 30 831 C2, which concerns a plant based sewage treatment system.